In 2013, Justin Trudeau – then leader of the third-place party – admittedto having smoked cannabis about a half-dozen times. He was unapologetic. He noted that the most recent occasion was during a dinner party at his Montreal home — well after his election to Parliament. Two years later, he became prime minister.

Not all Canadians have had the privilege of using cannabis without consequence.

Today, more than 500,000 Canadians are encumbered with a criminal record for doing something that is now legal: possessing a small amount (30 grams or fewer) of cannabis. A criminal conviction has real and lasting consequences. It can restrict the bearer's access to employment, housing, travel and the opportunities that accompany them. This impact is grossly disproportionate to the actual harm caused by the simple possession of marijuana.

Disproportionate consequences

The consequences of our officially outdated pot laws have not been evenly distributed amongst Canadians. As Prime Minister Trudeau acknowledged earlier this month: "There is a disproportionate representation of young people…from racialized communities who are saddled with criminal convictions…for simple possession." Black and Indigenous communities in particular have been historically overrepresented among this population.

Empirical evidence supports this. In Toronto, black people were three times more likely than white people to be arrested for possession. Black and Indigenous people have been similarly overrepresented in possession-related arrests throughout other major Canadian cities. The results are not only unfair, but also raise concerns about the extent to which the enforcement of the law has been consistent with the Charter of Rights and Freedoms, which guarantees the right to equal treatment under the law without discrimination based on race.

The federal government seems to recognize that convictions for simple possession of cannabis should no longer be a millstone, and Public Safety Minister Ralph Goodale has confirmed that it will facilitate pardons for people with such convictions.

While a positive development, pardons do not go far enough. If the Liberals are serious about eliminating past convictions as a source of future prejudice, they must expunge convictions for simple possession.

An expungement differs from a pardon in that it treats a conviction as never having been entered, permanently deleting it from criminal justice records. This effectively removes any burden it has placed on the holder for conduct our government now recognizes to be without stigma. It also has the benefit of increased certainty for the former record-holder, as the deletion of a record cannot be revoked. Moreover, a person whose record has been expunged can clearly and confidently state that they have never been convicted of a criminal offence.

By contrast, a pardon (technically called a "record suspension") maintains the record of the conviction, but effectively places it in a separate filing cabinet. A pardon can be revoked at a later date in certain circumstances. For example, the Criminal Records Act allows the parole board to revoke a pardon when it thinks someone is "no longer of good conduct" – a vague standard that can be met without someone even having been charged with a subsequent offence.

Most alarmingly, a future government could retract pardons for simple possession en masse by amending theCriminal Records Actor any separate legislation the current government introduces to implement this measure (though the validity of such an amendment would surely be challenged in court).

On what basis, then, does the federal government justify the half-measure of employing pardons rather than expungement?

Remedying injustice

Minister Goodale articulated the rationale: the injustice created by criminalization of simple possession is not sufficiently "unjust" to merit the expungement of these convictions. He pointed to the undeniable atrocity of criminalizing same-sex sexual activity as an example of the type of injustice that warrants expungement of convictions.

But if the goal is to remedy injustice, articulating a hierarchy of state-created injustices and their relative impact on marginalized communities is not a helpful exercise. Instead of trying to figure out whether an injustice was unjust enough to warrant expungement, the government should focus on how best to right a historical wrong.

In the case of convictions for simple possession of cannabis, the disproportionate harm it has exacted on black and Indigenous communities points to the expungement of convictions as the only way to permanently – and purposively – erase the scarlet letter.

The government also suggests pardons offer a travel-related advantage over expungement: if the United States has a record of a now-expunged conviction and denies entry, there will be no Canadian records to retrieve in support an entry waiver. This is not an insurmountable problem, were it ever to become manifest. Canada could explore issuing certified documents to former record-holders for use in a waiver application to U.S. authorities. The speculative benefit of pardonsis hardly overriding, particularly in light the U.S. Custom and Border Protection agency's recent statement that it does not recognizeforeign pardons.

Importantly, expungement would actually bring Canada into line with emerging trends in other jurisdictions. California has adopted a blanket, proactive expungement regime for minor possession convictions. State attorneys in two Vermont counties recently agreed to support the expungement of all old misdemeanour marijuana possession offences. States like Delawarehave adopted legislation to expunge records, while states like North Dakota are poised follow suit in permitting expungement.

It would be tragic if Canada's otherwise enlightened approach to cannabis were to falter on a question that disproportionately impacts marginalized Canadians. Justice and fairness demand that convictions for small possession of cannabis be meaningfully amnestied. Expungement is the only answer.